The objective of this proposal is to investigate if the avian hindbrain is responsible for inducing early inner ear folding via molecular cues. This is an unique study because much of the work on inner ear has been done after folding occurs. The specific aims of this proposal are: 1. to determine if folding is due to inductive influences from the hindbrain; and 2. if so, which soluble factors are involved in this induction. For the first specific aim, the approach will be to take advantage of the formation of ectopic vesicles when hindbrain tissue is rotated. In addition, removals of the hindbrain region adjacent to the future otic vesicle will be executed in whole embryo cultures. All manipulations are accomplished by using pulled micropipettes. For the second specific aim, the normal gene expressions in sections of placodes are compared to the same expressions in ectopic placodes. Most of the in situ procedures will require the use of fluorescent dendrimers by Polyprobe. These dendrimers are highly branched structures which carry thousands of labeled molecules. The dendrimers have significant advantages over radioactive oligonucleotides because they are safe to handle, and these structures amplify gene signals 100 fold greater than labelled oligonucleotides. This investigation may lead to other approaches in understanding human congenital deafness.